Why would you want any other site. The site that Bryant has given is the Lexmark official site with all the approved drivers. Just put in the appropriate model number etc and you should get what you want.
Having done a search etc, it would seem you need CJB4200EN.exe which is on Lexmark website. Lexmark 4200 Series All-In-One Driver ClickHere the description is a little confusing but if you do a web search they all seem to offer this CJB4200EN.exe as the printer driver. You could try the Universal Driver from Lexmark if that one doesn't work for you.